Heart valve prostheses have been used successfully since 1960 and generally result in improvement in the longevity and symptomatology of patients with valvular heart disease. However, 10-year mortality rates still range from 30-55%, and improvements in valve design are required to minimize thrombotic potential and structural degradation and to improve morbidity and mortality outcomes. Polymer trileaflet valves offer natural valve hemodynamics with the potential for sufficient durability for long-term use. Unfortunately these valves have not been successful to date because of long-term material degradation in vivo through a combination of oxidative reactions with blood and the high dynamic tensile and bending stresses borne by the material. This proposal describes a suitable material and appropriate valve design that will overcome these limitations. The goal of this Phase I SBIR project is to further the development toward commercialization of a novel polymer-based heart valve through a feasibility stage, where it will be demonstrated that the new valve will have a high likelihood of displaying sufficient biocompatibility along with improved hemodynamics and long-term durability over tissue valves in vivo. Answers to the following four questions are required for feasibility. 1. What is the appropriate material for the valve? 2. What is the appropriate design for the valve? 3. Can the valve be fabricated in a repeatable and reliable process? 4. Will the valve provide improved hemodynamics over commercially available tissue valves? Our preliminary results will demonstrate that much work has already been performed to answer these questions. To complete the feasibility analysis, the following specific aims will be performed. 1. Mechanical characterization of the polymer, including both static and dynamic analysis. 2. Comparative thrombogenic potential of the polymer material by measuring platelet deposition under controlled in vitro flow conditions. 3. Improved reliability and repeatability of the fabrication processes. 4. Comparative in vitro hemodynamics with an appropriate tissue valve.